Hi.

I initially wrote the following passage to post onto the official UK
Toyota Prius website - Users to users Forum under the Technology
section. After writing it I thought that some people on here may also
like to read it. For many it may be preaching to the converted and I
apologise for that. Others, particularly newcomers, may find it
interesting (I hope).......






I just thought that I would like to say how amazing the Prius
technology is. I am an electronics engineer and therefore can really
appreciate the very much played down or hidden technology in the
Prius.

For instance:

The THS inverter electronics (the big metal box in the RHS of the
engine bay). This little talked about module houses some amazing,
cutting edge and very high power solid state switching electronics.
It converts:

AC to DC (3 phase)

DC to AC (3 phase, variable frequency, 300V <80 Amps with pulse width
modulation for speed control)

300 Volts DC to 14 Volts DC at "lots" of Amps.

It even has it's own water cooling system with separate radiator and
electric pump (this is what makes the constant low pitched humming
noise you can hear when the key is on but the engine stopped)


Other stuff:

Electronic/electric power steering, runs off 12 Volts, totally
silent - amazing, try turning the wheel whilst stopped with key on
(engine warm and stopped), then turn key off and try again.

Electric servo assisted hydraulic brakes. (no vacuum available when
engine is stopped).

The regenerative braking system.

Traction control - won't let the front wheels be driven faster than
the rear wheels so preventing wheel spin.

Another electric water pump which cuts in when the engine is stopped
but only if the cabin heater is on. This gets heat from the hot
engine to warm the car whilst the engine is stopped. without this the
heater would soon blow cold when the engine stops as the mechanical
water pump also stops

No clutch, no torque converter, fixed gear train, in fact there is
actually no neutral gear or reverse gear as such (the gear shift
lever is essentially an electrical switch!), all of these functions
are achieved electronically with the innovative use of the planetary
differential gear set.

No throttle pedal linkage to the engine. The gas pedal is just a
variable resistor that tells the computer how much power the driver
is requesting. The computer has total direct control over engine
speed, fuel injection, ignition timing, valve timing etc. Truly this
is drive-by-wire! This is why it is technically so easy to add cruise
control, all the systems required are built right in anyway
(including the software! for it ) so why didn't they include the
switches to turn it on? Cest la vie.

No high voltage ignition distributor, rotor arm or spark plug high
voltage cables. The ignition coils, (4 of them!) are mounted right
inside the spark plug caps.

No starter motor or alternator. OK, so this has been done before, way
back, remember "Dynastart" But the implementation here is so much
more elegant.

No camshaft belt to wear out or replace, it uses a chain which should
last the life of the car!

Did you also know that the entire propulsion power from the engine
and motor combo is transmitted to the wheels via a CHAIN inside the
final drive gear box!!! Wow.

I could go on and on. This is truly an amazing car inside and yet
externally it is almost "too normal" for words. I am amazed by how
few people have even noticed anything about my car after driving it
around for 2 months now. I have even carried passengers who have just
said "nice car, why did you change from your last one?" Hmm, if only
they knew

Congratulations to the Toyota engineers, this is truly a remarkable
car and an amazing technological achievement.

Now if only it had Cruise control and a glove box light........


Peter
peter@...